The behavioral complexity, global distribution and status of the killer whale (Orcinus orca)
as a top predator indicate that this species plays a significant
ecological role in the marine environments that it populates. Most
research exploring the acoustics, movements and natural history of
these animals has taken place in British Columbia and Puget Sound, WA.
Because this animal’s tremendous behavioral variety is rooted in local
prey distributions and environmental features, this proposal describes
a study to be conducted on another population in Vestfjord off the
coast of northern Norway. The proposed research plan takes advantage of
a few long-term studies of the Norwegian killer whales, including a
catalog of almost 600 identified animals, records of pod composition
and detailed descriptions of a highly coordinated group foraging
context of corralling and incapacitating herring. We will synchronously
use multiple, new digital recording tags that attach non-invasively to
individual animals and continuously record their vocal behavior and
three-dimensional movements. In addition, a linear array of hydrophones
will be towed from a boat alongside the animals to localize all other
vocalizations produced by non-tagged group members. This field setup of
utilizing the tags and array in tandem will offer a unique view of how
these animals use sound to coordinate their traveling and social
hunting. The first set of objectives of this study use the ability to
assign calls to individual animals to assess whether their stereotyped
calls encode individually-distinctive features and how these features
propagate through their environment and the possibility of call
matching and exchanging between animals. A second objective is to
associate the timing and frequency content of the calls with the
movement data from the tags to test the hypothesis that acoustic
activity helps maintain the coordinated traveling and foraging
behaviors of the group. This will be the first research effort linking
vocalizations with continuous sampling of underwater movements of
free-ranging killer whales, offering a unique opportunity to ascertain
how vocal activity coordinates certain features of their behavioral
ecology in the wild.

Originally published: February 1, 2005

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